1. Field of the Invention
This invention relates to a Radiant Wall Oven and Process of Drying Coated Objects and is more particularly concerned with an oven having radiant walls, radiant heat transfer and turbulent air for convective heat transfer and to a process of using the same.
2. Description of the Prior Art
Infra-red energy has been used for years as a form of energy to cure and dry coatings. In most designs of infra-red ovens, gas burners or electric elements were usually used to produce the infra-red radiation. These burners or electric elements usually operated in a temperature range from 1200.degree. F. to 3000.degree. F. A typical gas fired infra-red burner of this type is described in Best U.S. Pat. No. 3,277,948 for RADIANT BURNER UTILIZING FLAME QUENCHING PHENOMENA. Because of the high energy levels generated at these temperatures, the burner surface area (radiating emitting surface) was usually small compared to the total area of the oven enclosure or compared to the absorbing surface area of the processed parts, material or objects which were to be heated and dried. Usually reflective material was mounted between the burners or electric elements to reflect the radiant energy that was not absorbed by the processed parts or material. As the reflectors aged and became soiled their reflective qualities decreased and the oven efficiency rapidly decreased.
One of the features of this invention overcomes this problem by providing a method and apparatus in which large surfaces, encompassing the entire tunnel of travel of the objects, can radiate; thereby eliminating the need for any reflective surfaces between emitting surfaces.
In the past, the automotive industry has usually employed, for painting its automobiles, lacquers and enamels, which air dried to a tacky free condition in several minutes. Recently, however, such automobile manufacturers have converted to acrylic enamels which stay wet substantially longer, thereby giving the paint more opportunity to be exposed to dirt in the ambient air. In substantially any type of oven, there is always dirt within the oven cavity which will be blown around by the air and may settle on the freshly painted, wet or tacky surface. To minimize the likelihood that dirt will reach the surface of the vehicle, the present invention will dry an acrylic paint, such as that paint used in the automobile industry, to a tacky-free condition in a relatively short period of time, namely in approximately six minutes, while maintaining the painted object in a substantially cleaner atmosphere and in a zone of air quiescence, thereby minimizing the likelihood of the collection of dirt and dust on the paint.